Jacobs was then posted to FA 11 (a reconnaissance squadron) for a year,
flying long-range sorties over Allied lines. His first victory over
a FrenchCaudron occurred in February 1916, however, it
was unconfirmed, due to lack of independent witnesses. He then
transferred to Fokker Staffel West (FSW), to fly Fokker E.IIIEindecker and finally achieved his first official victory,
either over an enemy balloon or aircraft. Fokker Staffel
West became Jasta 12 in October 1916, although a
month later Jacobs transferred to Jasta 22, then under the
command of Oberlt. Erich Honemanns, who was a personal friend. He
achieved his second victory (this time over a Caudron RIV) in
January 1917. He achieved three officially claimed and many more
unclaimed victories whilst at Jasta 22, where he remained
until August 1917, when he transferred to Jasta 7 as its
commander.

From early 1918 onwards, Jacobs started flying the Fokker Dr.Itriplane with Jasta
7, and had his aircraft finished in a distinctive black scheme. The
Dr I was his favoured mount until October 1918 and he used its
manouevibility to his advantage, becoming the triplane's highest
scoring ace, with over 30 confirmed victories.

After the war, he briefly became a flying instructor in the Turkish Army, before completely
withdrawing from military activity. He became a director in the
Alder works and later owned his own aircraft manufacturing company
in Erfurt in the 1930s. In addition to aviation, Jacobs was a keen
participant in bob sleighing and car and speedboat racing.

When the NSDAP came into power he became a Major in
the Reserves, although refused to join the Luftwaffe after being asked by Hermann
G√∂ring. Jacobs then moved his company to Holland during the World War 2 and at
one stage went into hiding, after refusing to let G√∂ring become a
major shareholder in his company.